GB2092959A

GB2092959A - Selective printing apparatus

Info

Publication number: GB2092959A
Application number: GB8103489A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-02-05
Filing date: 1981-02-05
Publication date: 1982-08-25

Abstract

Printing machinery for the printing of symbols of a large repertoire, especially such repertoires as the ideographs of Chinese script, comprises a stored fount 12 of symbols, and a first carrier area 8 on which images of individual symbols can be successively formed, e.g. developed from latent images, and which is re-conditionable to receive subsequent images from the fount after transfer of the first image in pigment form to a final carrier, e.g. paper on a drum 2. <IMAGE>

Description

SPECIFICATION Improvements in or relating to printing machinery This invention relates to printing machinery.

The invention is particularly concerned with the printing of symbols of a large repertoire, such as that involved in the printing of Chinese texts, in such a manner as to give direct legible copy without recourse to photographic development steps. This is in contradistinction to known systems whereby photographic masters are set up to produce page copy, the fount of symbols being stored in some form of optical store. It is also concerned with the possibility of printing such large repertoires without the need to dissect the individual symbols for some form of electronic storage, since this does not produce aesthetically tolerable symbols without resort to very large quantities of stored data.

The invention provides a printing machine for printing a sequence of symbols from a stored fount and which includes in combination: a] means to form a latent image of a given symbol on a first carrier area, b] means to convert the latent image to a pigment image, c] means to transfer the pigment image to a final carrier and, where appropriate, d] means to re-condition the first carrier to receive a latent image of a subsequently selected symbol.

The means to transfer the pigment image to a final carrier may include means whereby the pigment image is transferred from the first carrier area to at least one intermediate carrier, and from the or an intermediate carrier to the final carrier. The or each intermediate carrier may be disposable.

The invention has been devised with reference to selenium-surface electrostatic printing techniques, where the latent image is formed by an electrostatic charge pattern, but it could equally well be used with other kinds of latent image, for example magnetic or thermal latent images.

The fount of symbols may be stored in any suitable form, but optical storage is preferred, since it gives good quality images at reasonable cost. The latent image may be made with illumination emanating directly from the store, or alternatively a highintensity cathode ray tube may be driven from a vidicon or similar device which picks up the desired symbol.

It will be appreciate that the invention permits the provision of printed copy on plain paper by means of a device which does not require a large number of printing members, but by contrast uses a printing member on which any chosen symbol can be formed. This, coupled with optical storage on the fount, means that a flexible means has been provided to permit the printing of high quality symbols from any large fount.

The specific problem solved by the invention is that of printing Chinese texts. This problem is acute both in regard to the number of characters to be printed, which can be upwards of 8,000 different symbols, and in regard to the graphic information content ofthe individual characters, which in terms of dot-matrix representation require at least 2,000 dots to produce good quality printing. The only solutions of this problem of which I have been aware, and which do not involve dissection of the characters for storage, are variants of phototypesetting equipment, and cannot produce output which is either immediately visible, or on plain paper. The present invention permits the production of such output, and can be used to produce character printers or line printers.

The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a schematic vertical section through a first embodiment of the invention, and Figure 2 is a schematic view of a second embodiment of the invention.

The device illustrated in Figure 1 comprises a main body diagrammatically indicated at 1, which supports a platen roller 2 of the type commonly provided in a typewriter, and which can be driven for longitudinal movement and rotation in the usual manner. The roller 2 is covered with a yielding layer 3, and in addition to its conventional movements can be moved to and fro normally of its axis as indicated by the arrow 4. The reason for this will appear subsequently. The body of the device, then, is analogous to the housing of a conventional typewriter.

Pigment images of typographic symbols are applied to paper carried on the roller 2 by means of a printing head 5 rotatable about its axis as indicated at 6. The surface of the head 5 is coated with a layer of selenium, and is therefore capable of storing latent electrostatic images. The techniques applicable to this method of image production are wellknown and will be described only in outline. The surface of the head 5 may be electrostatically charged by a device indicated at 7, subsequent rotation of the head bringing the charged area to the region 8 for the reception of an optical image which thus becomes stored as a latent electrostatic image.

Further rotation of the head 5 brings the latent image into the region of a pigment applicator 9, where the latent image is converted to a pigment image. Finally the pigment image is brought to a printing alignment 10 when it is ready for transfer to the paper carried by the roller 2. This transfer to a final support is effected by the movement 4 of the roller 2, which brings the paper into contact with the head 5, the yielding of the layer 3 allowing the paper to make intimate contact with the head. The usual techniques for transferring and fixing the pigment image may be employed. Excess pigment is removed from the printing head at 11 to re-condition it for the reception of the latent image of a subsequent symbol.

The optical image which is received by the printing head is stored on a matrix 12 supported in the base of the machine 1. The matrix is movable in its own plane to bring any desired typographic symbol into register with the optical axis of the device. A flash tube 14, masked by an aperture 14a, serves to illustrate the symbol on the matrix, and a lens 15 focusses an image of the symbol, via a mirror 16, at the region 8. The light which will tend to enter the general region of the printing head from adjacent the platen roller 2 may be absorbed by light-trapping baffles 17a, 1 7b carried within the casing 17 of the device.

The sequence of events in printing each character thus involves setting the matrix 12 in the desired position to align the desired symbol with the optical axis 13, and then initiating the operation of the printing head 5 to bring an electrostatically charged area to the region 8. The flash tube 14 is then energised and the latent image formed. Completion of the operating cycle of the printing head presents a pigment image at the printing alignment 10, when reciprocation of the roller 2 is caused, thereby transferring the pigment image to the pauper. Once the image is suitably fixed, the carriage with its platen roller 2 is moved to bring the next chosen print position into alignment with the printing head in exactly the same manner as is used in normal typing.Assuming that the printing head 5 is arranged at the extreme left-hand end of the housing 17, this will mean that the character last printed is immediately visible on the page. Obviously the sequence of operations of the printing head 5 and the platen roller 2 should be carried out automatically once the action of printing a character has been initiated. The movement of the printing head will be effected by electric motor drive, but the movements of the roller 2 could be mechanically actuated, with the necessary spring drives, as in the case of a conventional manual typewriter. The movement of the matrix 12 may similarly be mechanically or electrically driven.Mechanical linkage to a suitable indicator mechanism is the crudest solution, but flexibility of use is enhanced if the matrix is driven electrically, since this provides a facility for remote operation, for example with the type of encoder described in New Scientist, Volume 77, pages 418 to 420.

Figure 2 illustrates the use of an intermediate carrier to provide a line printer. 2a indicates a platen which may be either rotary or flat, and a printing head 5a, analogous to the head 5 described above, is located beyond the right-hand end of the platen. A roll of narrow PTFE tape is mounted beyond the head 5a for transport across the platen 2a by means of a sprocket drive indicated at 19. The purpose of the tape 18 is to act as an intermediate carrier for the pigment images produced by the head 5a, and which are transferred to the tape by pressure from a member 20 moving along the line indicated by the arrow 20a. The tape may be electrostatically charged to ensure effective transfer of the image.As each successive pigment image is transferred to the tape, the latter is moved through one print position by the sprocket 19 until a full row of images is held across the paper on the platen. Then a heated roller 21 is moved along the line indicated by the arrow 21a to press the images against the surface of the paper.

The greater adhesion of the pigment to the paper in comparison to its adhesion to PTFE will ensure that the images transfer to the paper under the effect of heat and pressure, it being assumed that a heatsoftenable pigment is employed. Other means of transfer could, of course, be used, in which case alternative forms of intermediate carrier could be used. If these were to be too expensive to be discarded after use, an endless loop of the tape could be used, with provision for cleaning before re-use. It is also possible to provide means to take up slack in the tape between the printing head 5a and the platen 2a, thus allowing the tape itself to fulfil the function of a buffer two store pigment images during the step of transferring a completed line of images to the paper.

Although described with reference to electrostatic latent images, any form of latent image capable of conversion to a transferrable pigment image may be employed without departing from the invention, whose basis may be simply expressed as the provision in printing equipment of a printing memberwhich is repeatedly re-formable to print any desired symbol in immediately visible form. Again, although direct optical imaging has been described, it would equally be possible to use a cathode ray tube as an image source for the printing head, and to drive it either from a vidicon or like device exposed to stored images, or from an electronically stored fount. Equally obviously, other types of latent image may require different forms of storage and exposure to the fount.

CLAIMS (filed on 5th Feb 1982) 1. Printing machinery for printing a sequence of symbols from a stored font in which printing of images is effected via a printing member which lacks any inherent printable symbol but which is repeatedly reformable to provide transient images of the symbols of the sequence for successive transfer from the printing member to a final support.

2. Machinery according to Claim 1 wherein the printing member is re-formable in response to incident optical images.

3. Machinery according to Claim 2 wherein the printing member is re-formable by the agency of electrostatic charge.

4. Printing machinery for printing a sequence of symbols from a stored fount and which includes in combination: a] means to form a latent image of a given symbol on a first carrier area, b] means to convert the latent image to a pigment image, c] means to transfer the pigment image to a final carrier and, where appropriate, d] means to re-condition the first carrier to receive a latent image of a subsequently selected symbol.

5. Machinery according to Claim 4 and further including means whereby the pigment image is transferred from the first carrier area to at least one intermediate carrier and from the or an intermediate carrier to the final carrier.

6. Machinery according to Claim 5 wherein the or any of the intermediate carriers is disposable.

7. Machinery according to any of Claims 4to 6 wherein the latent image is produced as an electros taticcharge pattern.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the region 8. The light which will tend to enter the general region of the printing head from adjacent the platen roller 2 may be absorbed by light-trapping baffles 17a, 1 7b carried within the casing 17 of the device. The sequence of events in printing each character thus involves setting the matrix 12 in the desired position to align the desired symbol with the optical axis 13, and then initiating the operation of the printing head 5 to bring an electrostatically charged area to the region 8. The flash tube 14 is then energised and the latent image formed. Completion of the operating cycle of the printing head presents a pigment image at the printing alignment 10, when reciprocation of the roller 2 is caused, thereby transferring the pigment image to the pauper. Once the image is suitably fixed, the carriage with its platen roller 2 is moved to bring the next chosen print position into alignment with the printing head in exactly the same manner as is used in normal typing.Assuming that the printing head 5 is arranged at the extreme left-hand end of the housing 17, this will mean that the character last printed is immediately visible on the page. Obviously the sequence of operations of the printing head 5 and the platen roller 2 should be carried out automatically once the action of printing a character has been initiated. The movement of the printing head will be effected by electric motor drive, but the movements of the roller 2 could be mechanically actuated, with the necessary spring drives, as in the case of a conventional manual typewriter. The movement of the matrix 12 may similarly be mechanically or electrically driven.Mechanical linkage to a suitable indicator mechanism is the crudest solution, but flexibility of use is enhanced if the matrix is driven electrically, since this provides a facility for remote operation, for example with the type of encoder described in New Scientist, Volume 77, pages 418 to 420. Figure 2 illustrates the use of an intermediate carrier to provide a line printer. 2a indicates a platen which may be either rotary or flat, and a printing head 5a, analogous to the head 5 described above, is located beyond the right-hand end of the platen. A roll of narrow PTFE tape is mounted beyond the head 5a for transport across the platen 2a by means of a sprocket drive indicated at 19. The purpose of the tape 18 is to act as an intermediate carrier for the pigment images produced by the head 5a, and which are transferred to the tape by pressure from a member 20 moving along the line indicated by the arrow 20a. The tape may be electrostatically charged to ensure effective transfer of the image.As each successive pigment image is transferred to the tape, the latter is moved through one print position by the sprocket 19 until a full row of images is held across the paper on the platen. Then a heated roller 21 is moved along the line indicated by the arrow 21a to press the images against the surface of the paper. The greater adhesion of the pigment to the paper in comparison to its adhesion to PTFE will ensure that the images transfer to the paper under the effect of heat and pressure, it being assumed that a heatsoftenable pigment is employed. Other means of transfer could, of course, be used, in which case alternative forms of intermediate carrier could be used. If these were to be too expensive to be discarded after use, an endless loop of the tape could be used, with provision for cleaning before re-use. It is also possible to provide means to take up slack in the tape between the printing head 5a and the platen 2a, thus allowing the tape itself to fulfil the function of a buffer two store pigment images during the step of transferring a completed line of images to the paper. Although described with reference to electrostatic latent images, any form of latent image capable of conversion to a transferrable pigment image may be employed without departing from the invention, whose basis may be simply expressed as the provision in printing equipment of a printing memberwhich is repeatedly re-formable to print any desired symbol in immediately visible form. Again, although direct optical imaging has been described, it would equally be possible to use a cathode ray tube as an image source for the printing head, and to drive it either from a vidicon or like device exposed to stored images, or from an electronically stored fount. Equally obviously, other types of latent image may require different forms of storage and exposure to the fount. CLAIMS (filed on 5th Feb 1982)

1. Printing machinery for printing a sequence of symbols from a stored font in which printing of images is effected via a printing member which lacks any inherent printable symbol but which is repeatedly reformable to provide transient images of the symbols of the sequence for successive transfer from the printing member to a final support.

8. Machinery according to any of claims 4 to 7

wherein the fount of symbols is stored in an optical form.

9. Machinery according to Claim 8 wherein the symbols are stored in the form of direct optical images.

10. Machinery according to Claim 8 or Claim 9 wherein the latent image is formed in response to light emanating directly from the store.

11. Machinery according to any one of Claims 4 to 10 wherein the first carrier area is provided on the circumference of a rotatable member and drive and control means are provided to rotate the rotatable member after formation of the latent image whereby the latent image, converted into a pigment image, is presented at a position where the transfer of the pigment image is initiated.

12. Machinery according to any one of Claims 4 to 11 so constructed that a sequence of images may be produced before the first image in the sequence is transferred in pigment to the final support.

13. Machinery according to Claim 12 when appendent directly or indirectly to Claim 5 wherein at least one intermediate carrier is arranged to carry a sequence of images simultaneously prior to their transfer from that carrier.

14. Machinery according to any one of Claims 4 to 13 wherein the fount is stored as a set of reduced optical images carried on a transparent substrate.

15. Machinery according to Claim 14 wherein the substrate is electrically driven to bring any given image into register for projection on to the first carrier area.